Question

The Fovea centralis is
A. It is a region of a retina with only rod cell
B. It is a region of the retina without sensory cell
C. It is a region of the choroid with only cone cell
D. It is a region of the retina with only cone cell

Answer 1

Hint: Retina is a part of the eye where light is detected by photoreceptors and image is formed in the retina. Optic nerves connect to the retina and transfer the signal from the retina to the brain.

Complete answer: Fovea centralis is a small hole in the centre of macula lutea. In the macula, the fovea centralis contains only cone cells. Fovea centralis helps to make a sharp and clear image on the retina. Macula means ‘spot’ and ‘lutea’ means yellow. It is a highly pigmented and sensitive area on the centre of the retina. Macula lutea has a high number of cones cells. The half of the signal is sent to the optic nerve by the macula lutea portion on the retina. The yellow colour of macula lutea is due to the presence of a yellow pigment known as macular pigment. Mostly macula lutea contain a greater number of cone cells than rod cells. Mostly, the rod cells are present outside the macula lutea.
So, the correct option is D.

Additional Information: In the retina, there is a light-sensitive cell present known as photoreceptor cell. Two types of photoreceptors are present on the retina, i.e. rod cells and cone cells. Rods cells are rod-shaped and sensitive to dim light. They help to see in dim light and grey colour, whereas cones cells are cone-shaped and help to see in bright light.

Note: In the eye, the pupil is a small hole. Light passes through the pupil and reaches the retina. Pupils also protect the retina by controlling the amount of light. Suddenly, when we go in bright light, our pupil protects our retina by becoming small so that the light enters less in amount, and in dim light our pupil becomes large in size so that a large amount of light enters the eye.